DESCRIPTION (Investigator's Abstract): The studies outlined in this proposal are designed to investigate the overall arrangement of patterned neural connections in the primary visual area of the cat's cerebral cortex. The awareness that visual cortical areas contain regular modular arrays of neural connections has had a powerful influence on contemporary visual neuroscience. Much of the general appeal of this model of mammalian visual pathways comes from the fact that it is supported by evidence from a variety of species. To the extent that these data can be applied to mammals in general, they are of value in understanding the structure and function of the human visual system. On the other hand, the amount of evidence available from any single non-primate species is actually quite limited. For example, there has been almost none of these kinds of data for the cat, which is one of the more commonly studied animals in visual neuroscience experiments. The experiments of the present proposal are designed to build on the available evidence from the cat and determine the extent to which notions of the modular organization of striate cortex based on data from the monkey can be extended to the cat. The proposed studies will take advantage of the applicants laboratory's experience in revealing and then quantitatively analyzing tangentially arrayed periodic patterns of connections in cat striate cortex. A series of experiments will be conducted in which neuroanatomical labeling and staining techniques are used to visualize features of cortical neural reconstructions of these features and analyze them quantitatively. Data will be collected from both normally reared and visual deprived animals, in an effort to understand the brain mechanisms underlying human visual disorders such as amblyopia. The general significance of this proposal is that this comparative approach is crucial to the success of attempts to uncover common rules of mammalian brain structure and function. The outcome of these experiments will demonstrate whether the cat will continue to be a good model for carrying out further studies on patterned connections in visual cortex. To the extent that such studies are feasible in the cat, they should be encouraged for two reasons. First, they will reveal just how widely any putative general rules of mammalian brain structure and function can be applied. Second, they will indicate whether, in the applicants future efforts to understand the mechanisms underlying normal and abnormal human vision, it will be necessary to abandon the cat and move to the monkey, an animal that is both more costly and more difficult to acquire and maintain than the cat.